Arduboy Goes Thin and Flexible for Portable Gaming

We all have a gaming system in our pocket or purse and some of us are probably reading on it right now. That pocket space is valuable so we have to budget what we keep in there and adding another gaming system is not in the cards, if it takes up too much space. [Kevin Bates] budgeted the smallest bit of pocket real estate for his full-size Arduboy clone, Arduflexboy. It is thin and conforms to his pocket because the custom PCB uses a flexible substrate and he has done away with the traditional tactile buttons.

Won’t a flexible system be hard to play? Yes. [Kevin] said it himself, and while we don’t disagree, a functional Arduboy on a flexible circuit makes up for practicality by being a neat manufacturing demonstration. This falls under the because-I-can category but the thought that went into it is also evident. All the components mount opposite the screen so it looks clean from the front and the components will not be subject to as much flexing and the inputs are in the same place as a traditional Arduboy.

cost = low, practicality = extremely low, customer service problems = high

     ~[Kevin Bates]

These flexible circuit boards use a polyimide substrate, the same stuff as Kapton tape, and ordering boards is getting cheaper so we can expect to see more of them popping up. Did we mention that we currently have a contest for flexible circuits? We have prizes that will make you sing, just for publishing your flex PCB concept.

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Bone Conducting Headphones Built Into Eye Glasses

There are times when being seen to listen to music through headphones might get you into trouble. For these moments, reach for a handy solution: bone conduction speakers that discreetly pipe the music to your eardrums through the bone of your skull. [Samuel] wanted just such a covert music listening device, so created his own in a set of 3D-printed glasses.

He first tried using an Adafruit bone-conducting transducer but found that to be too bulky. What you see here is a smaller module that [Samuel] found on AliExpress (search for bone conduction module). The GD-02 is much smaller and thus more suitable for hiding in the arm of a pair of glasses. For the rest of the electronics he used a PCB and battery from a donated set of broken Bluetooth headphones, a space for which he was able to conceal easily in the 3D-printed frame of the glasses. The battery is in one arm and the board in the other, and he says the wiring was extremely fiddly.

The result is a surprisingly svelte set of specs that you might not immediately think concealed some electronics. His choice of bright yellow filament might give the game away, but overall he’s done a great job. This certainly isn’t the first bone conduction project we’ve shown you, some of the others have used motors instead of bone conduction transducers.

Benchtop Lathe Gets An Electronic Leadscrew Makeover

The king of machine tools is the lathe, and if the king has a heart, it’s probably the leadscrew. That’s the bit that allows threading operations, arguably the most important job a lathe can tackle. It’s a simple concept, really – the leadscrew is mechanically linked through gears to the spindle so that the cutting tool moves along the long axis of the workpiece as it rotates, allowing it to cut threads of the desired pitch.

But what’s simple in concept can be complicated in reality. As [Clough42] points out, most lathes couple the lead screw to the spindle drive through a complex series of gears that need to be swapped in and out to accommodate different thread pitches, and makes going from imperial to metric a whole ball of wax by itself. So he set about building an electronic leadscrew for his lathe. The idea is to forgo the gear train and drive the leadscrew directly with a high-quality stepper motor. That sounds easy enough, but bear in mind that the translation of the tool needs to be perfectly synchronized with the rotation of the spindle to make threading possible. That will be accomplished with an industrial-grade quadrature encoder coupled to the spindle, which will tell software running on a TI LaunchPad how fast to turn the stepper – and in which direction, to control thread handedness. The video below has some great detail on real-time operating systems on microcontrollers as well as tests on all the hardware to be used.

This is only a proof of concept at this point, but we’re looking forward to the rest of this series. In the meantime, [Quinn Dunki]’s excellent series on choosing a lathe should keep you going.

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Cocktail Barbot Takes Things Up A Level

Mixing a cocktail is considered as much an art as a science. The practice is studied dilligently by bartenders the world over. Of course, for any given human task, there’s always another human building a robot to automate it. [CamdenS5] is one such human, with a cocktail mixing barbot with a few tricks up its sleeve.

As you’d expect, there’s a smattering of the usual alcoholic liquids and mixers, along with a battery of pumps for fluid delivery. The fun doesn’t end there, though. There’s a linear actuator capable of putting out 500 N for slicing limes, and a mint and sugar dispenser as well. If that wasn’t enough, there’s even a muddling station to help bring out the flavours just right.

This is a machine that takes a broader look at the process behind making a good cocktail. It’s not just about lumping ingredients into a glass – it takes finesse and care to get the best results. It’s not the first barbot we’ve seen – this one is built in a grandfather clock.

Add-Ons Go Electroluminescent

It’s that time of the year again, and once more we’re faced with the latest innovations in Badgelife, the movement to explore the artistic merits of electronics and manufacturing. This is an electroluminescent printed circuit board, and it’s some of the finest work we’ve seen. It’s also a Shitty Add-On that glows blue.

The process for applying an electroluminescent coating to printed circuit boards is, surprisingly, something we’ve covered before. Late last year, [Ben Krasnow] delved deep into a DIY EL display. The process is expensive, but all the products come from a company called Lumilor. The first step in this process is applying a thin conductive coating on a substrate with an airbrush. Since the entire idea of printed circuit boards is to have a layer of conductive material etched into any shape you want, the simple circuit board is the idea experimental platform for playing with EL displays. Traditionally, EL displays were made entirely with a silk screen process, like [Fran]’s ongoing attempt to recreate the Apollo DSKY display.

The electronics for this badge are simply a Microchip MIC4832 EL Driver, which converts the 3.something volts from the add-on header into 100 or so Volts AC at hundreds of Hz. This is a single-chip solution to driving EL displays, and the only other parts you need are an inductor, diode, and a few caps and resistors. An ATtiny85 can be used to blink the circuits, or, alternatively, you could copy [Ben]’s work and build a character EL display.

The process of applying an electroluminescent coating to a PCB does require a spray gun or airbrush, and the chemicals are a bit expensive. This, though, is pushing the boundaries of what can be done with artistic PCBs. It’s new applications of technology, simply as wearable electronics. It’s the best example of the possibilities of the medium and some of the best work that’s come out of the Badgelife scene.

Pocket Watch Becomes Pinhole Camera

A pinhole camera is essentially the combination of the camera obscura with photographic film. The pinhole acts as the lens, focusing the scene onto the film, and after exposure, the film can then be developed and you’ve got your picture. They’re a fun way to learn about photography, and easy to make, too. [Brooklyntonia] decided to undertake just such a build, secreted away inside a pocket watch.

The build starts with with the disassembly of the watch, which acts as the main cavity of the camera. A bellows is then constructed from leather and a toilet paper roll to allow the camera to still fold up inside the original watch case. A pinhole is then installed at the end of the bellows, and a plug is used as a shutter to allow the bellows to be properly unfolded prior to exposure.

It’s a fun build, and one that comes complete with instructions for the proper processing of film in your own darkroom – or bathroom. Pinhole cameras can be useful tools, too – particularly for things such as capturing an eclipse.

The Science Of Reverse Mounted LEDs

One of the most artistic applications of electrical engineering in recent memory is the burgeoning badgelife movement. This is an odd collective of people who are dedicating their time to rendering their own accomplishments in printed circuit boards. Of the entire badgelife collective, one of the most visible efforts are in Shitty Add-Ons, with a particular focus on reverse-mounted LEDs. Yes, you can install SMD LEDs upside down, and if you have your copper layers right, the light will shine through the badge.

One of the most prominent users of reverse mounted LEDs is [TwinkleTwinkie], and now finally we have a writeup on the science of reverse mounted LEDs. There’s a lot to unpack here, so buckle up and prepare to burn the tips of your fingers on a soldering iron.

For truly reverse-mounted PCBs, there are two options. The first, and most expensive, are ‘reverse gullwing’ LEDs. These LEDs are just like normal LEDs, except the SMD pads are reversed, allowing you to mount it so the light shines into the PCB. These LEDs are expensive, rare (only three companies make them), and they don’t really give off a lot of light. The other solution to reverse-mounting a LED is simply taking a standard 1206 SMD LED and manually soldering it upside-down. This is not pick and place friendly, although I’m sure you could find an LED manufacture that would put LEDs in reels upside-down if you want.

Side view LEDs

The takeaway for reverse mount LEDs is pick two: good, fast, or cheap. Reverse gullwing LEDs are expensive, but can be pick and placed and provide sufficient illumination. Hand-soldered LEDs installed upside down are cheap, slow, but also good.

But there is another option. Side view LEDs are a thing, and they can be pick and placed. You can get them in every color, and even UV. [Twinkle] has experimented with side-view LEDs in place of reverse mounted LEDs, and the results are promising. By putting the side view LED next to part of a PCB without copper or soldermask, there is some light bleed through the PCB. It’s somewhat uneven, but with a hot melt glue diffusor, you can get a somewhat decent bar of light being emitted through a PCB.

If you want to put blinky on a PCB, you have a lot of options. If you want to put blinky on a PCB without having any visible light source, these are your options. This is the state of the art in artistic PCBs, and we’re so glad [Twinkle] could share it with us.